In the context of some other devices, quite a bit. For example, a project
my company did used a flash chip which had a byte-write time of about 10us
and a block-erase time (no byte erase) of over a second. Generally, from
my limitted experience, MOST chips which use EEPROM are byte eraseable and
have comparable write/erase times, while most chips which use flash are only
block-erasable and have highly asymetric write/erase times.